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RCS is defined as : and given by : Radar Cross Section (RCS) The absolute magnitude of RCS is given in terms of area, typically in units of square meters (m 2 ) Relative magnitude is given in terms of dBm 2, where RCS is the area a target would have to occupy to produce the amount of reflected power (echo) that is detected back at the radar.

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RCS frequency regions :  Rayleigh Region (low frequencies) Target dimensions are much less than the radar wavelength (l<< ). In this region RCS is proportional with the fourth power of the frequency  Resonance Region (medium frequencies) Target dimensions and the radar wavelength are in the same order (l  ).  Optical Region (high frequencies) Target dimensions are very large compared to the radar wavelength (l>> ). In this region RCS is roughly the same size as the real area of target.

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Radar Cross Section (RCS) RCS of a target is dependent on several factors, such as,  Orientation (Viewing direction)  Radar frequency  Polarization of the radar signal (vertical, horizontal, circular)  Physical size of the target  Geometry of the target  Composition of the target (Surface Quality) When RCS of a target is of interest these parameters should be given :  Angle of incidence  Angle of scatter  Incident field polarization  Scattered field polarization  Frequency and target geometry  RCS value

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Radar Cross Section (RCS) Cross Section of Real Targets The cross section of complex targets are complicated functions of the viewing aspect, frequency and polarisation. The most accurate method of determining the cross section of a target is by measurement. However it is often impractical to measure this over all aspect angles in azimuth and elevation. Target cross section is often related to their physical size, but under certain circumstances it may be much larger. For example a corner reflector has an extremely large target cross section in relation to its size, whereas a B2-B stealth bomber has a very small cross section.The RCS of a B26 bomber exceeds 35 dBm 2 (3100m 2 ) from certain aspect angles. In contrast, the RCS of the B2 stealth bomber is about – 40dBm 2. Because it is made up of reflections from a large number of scatterers, even very small changes in the aspect angle of the target results in relative phase changes between the scatterers and an altered cross section. Experimental cross section of the B-26 two engine bomber at 10 cm wavelength as a function of azimuth angle Experimental cross section of a Toyota pickup truck at 35 GHz as a function of azimuth angle